Glider trucks, which are made by putting old engines into new frames, have become a political hot potato. Back in October 2016, the U.S. Environmental Protection Agency (EPA) and the National Highway Traffic Safety Administration (NHTSA) published a final rule limiting the production of glider trucks that take advantage of a regulatory loophole. The loophole leaves glider trucks, also called glider kits, subject only to the emissions standards of the year the engines were first built, not the year they are retrofitted. EPA first established emissions standards for trucks in 1974, and between 2007 and 2010, phased in the last major set of standards targeting particulate matter and nitrogen oxides (NOx). By using engines from the 1990s and early 2000s, the glider kit industry found a way to skirt these more stringent standards. A study conducted at the National Vehicle Fuel Emissions Laboratory (NVFEL), an EPA facility located in Ann Arbor, MI, found that these trucks’ particulate matter and NOx emissions can be dozens of times higher than those of trucks that meet current standards for new vehicles.

Sales of glider kits are on a steep rise: 1,000 were sold in the United States in 2010, and by 2015, that number had risen to 10,000. The 2016 EPA rule required these vehicles to meet the emissions standards from the year of assembly, lowering overall greenhouse gas emissions in line with President Obama’s 2013 Climate Action Plan, and additionally providing “substantial public health related benefits” by reducing particulate matter and NOx emissions from truck exhaust. Exceptions were made for small businesses employing 1,500 or fewer employees. These small businesses would be capped at 300 new glider trucks per year, with fewer allowed for businesses that had produced less than 300 vehicles in the years leading up to the regulation. This cap, which would have taken effect in January 2018, has since become a political quagmire. While the Trump administration continues a pattern of deregulation, attempts at repealing the cap and excluding glider kits from updated emissions standards have been hindered by legal challenges and institutional checks.

The Obama-era rule is strongly opposed by many owner-operator truckers, who own or lease their vehicles and view glider kits as a more economical alternative to traditional new vehicles. Most of them are represented by the Owner-Operator Independent Drivers Association (OOIDA), which today has around 160,000 members in the United States and Canada. Glider kits are roughly 25 percent cheaper than traditional new trucks, and Fitzgerald Glider Kits, the leading manufacturer of glider kits, advertises them as environmentally friendly, easy to maintain, and reliable. Although the company’s website calls glider kits “a form of recycling,” and highlights the carbon emissions avoided by reprocessing steel for new engines, a coalition of health and environmental advocacy groups, including the American Lung Association and the Environmental Defense Fund, support capping glider truck production and requiring all trucks to meet the emissions standards from the year of assembly. EPA recognizes diesel exhaust as a likely carcinogen, and public health officials warn that one of its components, NOx, is responsible for the formation of smog. Smog can cause cardiovascular problems, respiratory illness and may aggravate asthma, especially for children who spend much of their time outdoors.

Some opponents of the rule do not trust the EPA study that evaluated glider kit emissions. In a September 13, 2018, hearing, Congressman Andy Biggs (R-AZ), chairman of the Subcommittee on Environment in the House Science, Space, and Technology Committee, called the 2016 rule “politically driven,” and questioned the study’s methods and integrity. He and other opponents of the rule allege that Volvo Group, a truck manufacturer in competition with the glider kit industry, had undue influence and helped EPA’s NVFEL obtain test glider trucks. On behalf of EPA Acting Administrator Andrew Wheeler, Assistant Administrator Bill Wehrum sent a letter to the House Science Committee defending the NVFEL facility’s procedures and denying claims that Volvo Group shaped the outcome of the study. The other notable study on glider kit emissions, conducted at Tennessee Tech University and used to support the claim that glider truck emissions are comparable to those of traditional new trucks, also faces criticism. University President Philip Oldham wrote a letter to former EPA Administrator Scott Pruitt requesting that the Tennessee Tech study not be used or referenced, and informed him that the study was under internal review for potential research misconduct. At the September 13 hearing, Paul Miller, Deputy Director & Chief Scientist for Northeast States for Coordinated Air Use Management, highlighted the “implausibility” of a reused glider truck engine producing emissions comparable to a new engine that has been built to comply with updated standards.

Under the Clean Air Act (CAA), EPA has the authority to set emissions standards for new motor vehicles in the interest of protecting public health and welfare. In its 2017 proposal to repeal the Obama-era glider truck regulation, EPA advanced an interpretation of the CAA that stated any vehicle classified as new must also be equipped with a new engine. This interpretation would effectively undermine the agency’s authority to regulate the glider kit industry. Additionally, EPA argued that repealing the rule would be a “deregulatory” action, and should therefore not require that the agency prepare a Regulatory Impact Analysis (RIA). RIAs are developed to weigh the costs and benefits to society for proposed regulatory changes when they are expected to have a significant effect. The EPA is also legally mandated to create a public comment period as part of this rulemaking process, after which it must address any serious concerns or objections. The original public comment period for the repeal of the glider truck rule ended January 5, 2018. The White House Office of Management and Budget has instructed EPA to conduct and submit an RIA with its proposed repeal, and if it does submit an RIA, there must be a new public comment period. On July 6, 2018, former EPA Administrator Scott Pruitt issued a “No Action Assurance,” meaning that the cap on glider trucks would not be enforced for at least one year. But following a series of legal challenges, Andrew Wheeler, in his new role as acting administrator, withdrew Pruitt’s “No Action Assurance” just three weeks later, calling it an inappropriate application of the agency’s enforcement discretion. On paper, this means the cap will be enforced; however, the future of the glider truck rule remains uncertain.